On Mon, Mar 07, 2022 at 07:03:17PM -0500, Marek Polacek via Gcc-patches wrote: > In r270550, Jakub fixed classify_insn to handle asm goto: if the asm can > jump to a label, the insn should be a JUMP_INSN. > > However, as the following testcase shows, non-null ASM_OPERANDS_LABEL_VEC > doesn't guarantee that the rtx has any actual labels it can branch to.
But it should. > Here, the rtvec has 0 elements because of the __thread variable: we perform > ix86_rewrite_tls_address which calls copy_isns and that allocates the rtvec: > > XVEC (copy, i) = rtvec_alloc (XVECLEN (orig, i)); So fix *that* instead? Everywhere else does not use length zero RTL vectors. copy_rtx makes sure to do the right thing here, for example. We do not have notation to create zero-length vectors in RTL source code either, btw.: case 'V': /* 'V' is an optional vector: if a closeparen follows, just store NULL for this element. */ (optional vectors are at the end of an RTX), and if you write [] you will hit fatal_with_file_and_line ("vector must have at least one element"); Segher